While implant generally means a replacement of a specific section of a human body, it means grafting of an artificial tooth in dentistry.
The implant is a hi-tech operation method by which upon the occurrence of loss of the root of a tooth, an artificial dental root made of titanium, which is not rejected by the human body, is implanted in alveolus from which the tooth was removed, and an artificial tooth then is fixed thereto to recover an original function of the tooth. In comparison with a common prosthesis or denture, which causes the neighboring teeth and bone to be damaged as time passes, the implant has advantages in that it does not have a bad influence on the neighboring tooth, and that it is usable for a long time since it prevents tooth decay while being of similar function and shape to that of the natural tooth.
However, it was reported that the success rate of the implant at the maxillary posterior teeth was comparatively lower than that for other parts. This is because the maxillary posterior teeth are weak and the maxillary sinus exists near the maxillary posterior teeth, so that a long implant cannot be placed into the maxillary posterior teeth.
That is, since the maxillary sinus existing in the maxillary is the space surrounded by a mucous membrane, when a tooth is lost, the maxillary sinus physiologically falls down and widens greatly and the downward extension of the maxillary sinus and the osteolysis owing to the loss of teeth occur, resulting in a lack in the amount of bone into which the implant can be placed, making it difficult to carry out the implantation for the maxillary posterior teeth.
Meanwhile, as a representative operating method of the related art in the case of the occurrence of a lack in the amount of bone up to the maxillary sinus, the two operating methods are as follows: a lateral approaching method in which a lateral window (hole) is formed below a malar bone, a maxillary membrane is directly lifted there through, and a graft material is filled between the inferior margin of the maxillary sinus and the maxillary membrane; and a vertical approaching method using an osteotome.
First, the lateral approaching method is an operating method for the placement of a long implant at a maxillary posterior tooth, which is greatly deficient in the amount of bone in a vertical direction (remaining bone is 5 mm or less), wherein the method is carried out so that a sidewall of a maxillary is removed in consideration of the height of the remaining maxillary extending up to the maxillary sinus 100, and the amount of bone is secured through bone grafting.
In specific, the lateral approaching method includes a process of harvesting bone fragments of a patient in order to graft a bone to a portion where the amount of a bone is deficient from a bone section other than the section to be operated on (if it is difficult to harvest bone fragments from the patient, artificial bone is used), a setting process of creating an incision line to a vestibular region of a section corresponding to a molar tooth, a forming process of forming a mucoperiosteal flap, a windowing process of windowing a facial wall of maxillary sinus through fracture line formed using a round bur, a piezo sawtooth, or a diamond tip, after windowing, a lifting process of lifting the facial wall of the maxillary sinus and a membrane of the maxillary sinus, a treating process of treating a space in the maxillary sinus whose bone plate is lifted, a grafting process of grafting a bone, a suturing process, and a placement process of placing an implant 6 to 12 months after the operation.
However, such a lateral approaching method is very difficult to do and is a careful, time-intensive process because especially during the windowing is the maxillary sinus often punctured in the process of using the round bur, the piezo sawtooth, or the diamond tip, resulting in the symptoms of swelling and pain.
Further, the vertical approaching method is an operating method implemented when the amount of the remaining bone is slightly deficient (e.g. 5 to 10 mm), wherein a bone is lifted using a chisel such as osteotome, or the remaining bone is removed using a special drill or reamer, an autogenous bone or an artificial bone is grafted into that space and an implant is placed there.
That is, the vertical approaching method is carried out so that a hole is formed using a drill at a portion where an implant is placed, osteotomes (each having diameters ranging in size from small to large) are inserted in a series into the hole and are hammered so as to gradually enlarge the hole, approach the maxillary membrane so as to fracture only a bone without damaging the membrane, an autogenous bone or an artificial bone is grafted in that space, and the implant is placed there.
In specific, the vertical method includes a process of forming the hole using a twist drill extending to a stable distance which does not however reach the maxillary membrane, i.e. up to a compact bone below the maxillary membrane, a process of sequentially inserting and hammering the osteotomes having diameters varying from a small size to a large size into the hole so as to form a hole corresponding to a diameter of the implant, and upon formation of the hole suitable to implant placement, a process of finally and carefully hammering the osteotome so as to fracture the compact bone, a process of filling the hole of the compact bone with a bone graft material, a process of softly hammering the osteotome into the hole filled with the bone graft material so as to lift the maxillary membrane, and then a process of removing the remaining bone using the special drill or reamer, a process of lifting the maxillary membrane using the graft material until a height of an available bone is secured such that the implant can be placed through that height, and a process of placing the implant.
However, despite that such a vertical approaching method has the advantage of few occurrences of edema occurring in patients after operation because of the narrow target section of the operation, a long time is spent operating since during operation a dentist cannot directly observe the maxillary membrane so that he must operate very carefully while checking the target section via X-ray, a patient feels very unpleasant owing to the striking which is done during the operation, and particularly when the drill comes into point contact with the maxillary membrane as the tip thereof rotates is a vertical load concentrated upon the contacted maxillary membrane thereby easily fracturing the same.
That is, while the special drill or reamer does not fracture the remaining bone of the maxillary membrane since it is not hammered (so that it causes only a little pain to the patient), it has a very small operating force so as to be insufficient to puncture the maxillary membrane, so that it takes too long of a time to remove the same. Further, if the maxillary membrane is of an irregular shape or is severely inclined, the drill or reamer can puncture the maxillary membrane while removing the remaining bone, making it difficult to maintain in place the bone graft material for forming the bone material. This allows the implant to be exposed to the outside in the maxillary membrane without being placed in the bone, thereby increasing the possibility of infection and degrading the capability of supporting the implant because of a lack in the amount of support bone.
Therefore, recently there has been proposed a piezoelectric device which has been known to be advantageous to the protection of the weak maxillary membrane upon the formation of a window or then the lifting of the maxillary membrane because unlike the existing method, it hardly punctures or tears the maxillary membrane even when coming into contact with the same. A conventional piezotome unit used in the piezoelectric device is an ultrasonic device which is bent like a “” so that it can easily approach the maxillary sinus. However, since it has no structure for preventing the maxillary membrane from becoming damaged through a construction which does not excessively penetrate into the target section of the operation after removal of the remaining bone, it is impossible to implement lifting in a stable state, so that if a dentist applies an excessive force to the target section, the maxillary membrane is as a result frequently punctured. Therefore, there is a need to provide a piezotome unit capable of solving the above problems.